GB2268114A - Manufacture of a golf club hand grip - Google Patents

Abstract

The invention is a method of making a hand grip comprising injection moulding the grip from a synthetic elastomeric thermoplastic material. The mould cavity in which the grip is to be cast may have an interior surface which is textured (e.g. by spark erosion) to form a correspondingly textured surface on a grip formed in the mould. The mould cavity may comprise two generally cylindrical parts which are disposed generally concentrically to define the cavity therebetween. The method may comprise applying a marking to the grip by hot foil printing.

Description

TITLE: GOLF CLUB GRIP DESCRIPTION The invention relates to a hand grip for the handle of an implement and more particularly but not exclusively, to a hand grip for a golf club.

The design of golf club hand grips is controlled by Rules imposed by the Royal and Ancient Golf Club of St.

Andrews and by the United States Professional Golf Association. Thus golf club grips are generally cylindrical in shape and taper from a relatively thick top end remote from the head of the club to a relatively thin lower end part-way down the shank or shaft of the golf club. Many golf club grips are provided with markings very often in a chevron pattern and such markings are either decorative or are intended to improve frictional contact of the golfer's hands on the grip to prevent slipping during use.

Golf club grips are made from a wide variety of materials such as rubber, plastics and leather. Often such grips are moulded from rubber and are usually manufactured with recesses in the moulding, both to produce a pattern, and so it is claimed, to improve the user's grip. The opposite may in fact be true for the reasons explained below.

It is conventional for rubber grips to be compression moulded, which causes a heavy flash on the part. This heavy flash is wasteful of rubber, causes unnecessary moulding tool wear, and is difficult to remove cleanly.

Conventionally the mouldings are then dipped or sprayed so that they are entirely coated with paint. The mouldings are then buffed to remove surplus paint, leaving paint in the recesses to show up the patterns formed thereby.

This is a time consuming process. It is also wasteful of rubber and paint. In addition although the buffing process produces a surface of good frictional qualities when new, it destroys the grip's natural water repellency formed by the "skin" of the rubber moulding, which makes the grips difficult to hold during wet conditions. The same applies during hot conditions when hands become wet with perspiration. Because, in effect, wear is already begun during the manufacturing process by buffing the grips, the abrasion resistance of the grips is also decreased.

Compression moulding is a slow form of rubber product manufacture and accordingly, wage and press heating costs are higher than with other forms of rubber moulding. As a general point concerning the manufacture of grips in the conventional fashion, costs for moulding tools are high because raised parts have to be included in the cavity to create recesses in the rubber moulding.

I have found that to some extent these difficulties can be overcome by injection moulding the rubber using a transfer injection moulding machine in which a rubber block in a first cavity is heated and then squeezed through an injection port into a second cavity in which it is formed to the desired finished shape. This moulding method does not however provide the whole answer for the reason that it is impossible to print, eg a decoration or a maker's name or trade mark, in a permanent and satisfactory fashion onto the moulded grip. Presumably it is at least to some extent for this reason that the existing method of applying paint into recesses on the grip and of buffing off the surplus paint has been employed for so long in spite of its inherent defects.

It is an object of the invention to provide an improved method of making grips.

According to the invention there is provided a method of making a hand grip comprising injection moulding the grip from a synthetic elastomeric thermoplastic material.

Such materials, e.g. that sold by the Nonsanto Company under the trade mark SANTOPRENE, combine the performance characteristics of vulcanised rubber with the ease of processing of thermoplastics and can be successfully and permanently printed as required.

Preferably the method comprises providing a mould having a mould cavity in which the grip is to be cast, the interior surface of which is textured to form a correspondingly textured surface on a grip formed in the mould. Preferably the textured surface of the mould cavity is formed by spark erosion. Preferably the mould cavity is substantially free from projections of the kind adapted to form paint-receiving recesses in the surface of the grip.

If desired, however, the mould cavity may have relatively few projections, eg a single longitudinal projection adapted to form a recess in the grip to indicate the golf club centre-line.

The mould may have a mould cavity made from two more or less identical parts, the mould being split longitudinally of the grip to allow a finished grip to be removed from the mould. This arrangement will tend to give an opposed pair of mould lines extending axially of the grip. Preferably, however, the mould is not split in this way and is instead closed at one axial end whereby the grip can be removed axially through the said one end of the mould so that the moulding marks are less obtrusive.

Preferably a pattern will be applied to the grip by hot foil printing.

Advantages of this method are: 1. little material waste as scrap can be recycled; 2. easy trimming of flash; 3. reduced moulding tool wear; 4. a higher rate of production, a reduction in mould change time and more cavities can be included in the moulding tool; 5. because of all the above, heating and wage costs are reduced, and 6. close control of the weight of the grips. This is important with a grip for a golf club.

The texturing of the inner surfaces of the moulding tool eliminates part of the need to buff the grips. Thus grips can be manufactured with an attractive and practical textured finish and they will show superior abrasion resistance to ordinary grips, because they have not been buffet.

Also because there is no buffing, the rubber will retain its natural water repellency (water will bead, and will be easily wiped away). The textured surface of the grip will make it secure in the golfer's hands, thus allowing for a lighter hold to be taken. The resultant relaxation of the wrists will, in turn, facilitate longer, straighter shots.

Apart from a centring line, the grips will preferably be manufactured with no other recesses, thus allowing the maximum surface area of the grip to come into contact with the golfer's hands.

Another advantage of the method is that custom prepared grips for clubmakers are easily and cheaply manufactured.

Patterns can be printed directly onto the grips' outer surface, preferably using a hot foil process. This method of printing is quickly and easily applied. The process offers versatility of design and colour and new printing blocks are easily and cheaply manufactured to cater for different customers' requirements.

The invention is diagrammatically illustrated by way of example in the accompanying drawings in which: Figure 1 is a side view of an injection moulding apparatus partly in section; Figure 2 is a sectional view of a mould, showing the mould cavity; Figure 3 is a side view of a hot foil printing machine.

Figure 4 is a diagram illustrating the printing process; Figure 5 is a sectional end elevation showing how the grip is supported during the printing process, and Figure 6 is a side view of a grip.

In the drawings a golf club grip 1 is made to conform to the standards imposed by the Royal and Ancient Golf Club of St. Andrews and the standards imposed by the United States Professional Golf Association so that it is generally cylindrical in shape and tapers gradually from a relatively thick upper end 2 to a relatively thin lower end 3. The grip is injection moulded from a thermoplastic elastomeric material, such as that sold by the Monsanto Company under the trade mark SANTOPRENE, which resembles vulcanised rubber.

The moulding apparatus is illustrated in Figures 1 and and injects a measured dose of the elastomer into the mould cavity of a moulding tool through one axial end of the cavity, through which the finished moulding is removed from the cavity.

As shown in Figure 2, the mould consists of a main block 4 containing a frusto-conical cavity 5 extending from one end 6 to the other end 7 of the block, and two end blocks 8,9 which close the frusto-conical cavity in the main block and which define the opposed ends 2 and 3 of the grip. As shown an injection port 10 is formed in one end 8 of the two end blocks defining the larger end of the grip. A bar 11 is disposed in the cavity to extend axially thereof and co-axially therewith so that the grip is formed as a hollow body. The interior of the cavity in the main block 4 is spark eroded to provide the required surface texture or finish to the grip to be formed in the cavity.

The grip can be removed from the mould cavity by applying compressed air at the smaller diameter end of the cavity 5.

By this method it is possible to avoid the formation of moulding lines along the moulding which would appear if the mould were axially split.

After a moulding 13 is removed from the mould cavity it is mounted on a mandrel 12 as shown in Figure 5 so that the grip can be printed by hot foil printing as shown in Figures 3 and 4, e.g. with the pattern or trade mark shown in Figure 6. The mandrel 12 is D-shaped in cross-section with the flat face 14 of the mandrel disposed opposite to a die block 15 of the hot foil printer so that the mandrel forms an anvil against which the portion of the grip to be printed will be formed during printing.

The method and apparatus of the present invention thus enables the production of hand grips, e.g. golf club grips, which are substantially improved as compared to known hand grips.

Claims (7)

1. A method of making a hand grip comprising injection moulding the grip from a synthetic elastomeric thermoplastic material.

2. A method according to claim 1, comprising the step of providing a mould having a mould cavity in which the grip is to be cast, the interior surface of which mould cavity is textured to form a correspondingly textured surface on a grip formed in the mould.

3. A method according to claim 2, comprising the step of forming the textured surface of the mould cavity by spark erosion.

4. A method according to claim 2 or claim 3, comprising providing the mould cavity to be substantially free from projections of the kind adapted to form paint receiving recesses in the surface of the grip.

5. A method according to any one of claims 2 to 4, comprising the step of forming the mould cavity from two generally cylindrical parts which are disposed generally concentrically to define the cavity therebetween.

6. A method according to any preceding claim, comprising the step of applying a marking to the grip by hot foil printing.

7. A method of making a golf club hand grip substantially as hereinbefore described.